Curtains for curtain side trailers are opened and closed by attaching the curtains to a trolley with rollers to a top rail on the trailer. Because these curtains are moved often, eventually the rails upon which the rollers roll become worn and must be replaced or repaired.
One solution to the aforementioned repair process has been to put a replaceable steel flange over the worn surface. These upper rail inserts appear to be held in by the rollers themselves. While this solution works to some extent, shifting of these prior art upper rail inserts will cause them to wear prematurely. Furthermore these upper rail inserts are not easily replaced in the field. Accordingly, there is a need for a better way to hold upper rail inserts in place.